Physical unclonable function (PUF) technology is a technology of obtaining unique random codes by using uncontrollable random variations in a process of manufacturing a semiconductor chip. The manufacturing variations include process variations of a semiconductor. Even if there are precise process steps that can manufacture a semiconductor chip, process variations are almost impossible to be replicated, such as film thickness distribution, micro defect distribution, ion implantation distribution and other random factors. Therefore, a semiconductor chip with the PUF technology is commonly applied to an application for high safety protection.
The current PUF implementation manners mainly include: a non-electronic PUF, such as an optical PUF; an analog circuit PUF, such as a coated capacitor PUF; a digital circuit PUF, such as a static random-access memory (SRAM)-based PUF; and the like. Among them, implementation manners of the non-electronic PUF and the analog circuit PUF are relatively complex, and integrating with a large-scale digital circuit are relatively inconvenient. Therefore, a structure of the digital circuit PUF is a relatively hot research direction of safety application in the field of integrated circuits at present.
The current digital circuit-based PUF implementation manners mainly focus on an SRAM-based PUF implementation, propagation delay-based and one time programmable memory (OTP) structure-based PUF implementations, and the like, where the SRAM-based PUF implementation may generate a certain bit error rate in a process of application, and each SRAM unit circuit is relatively complex and cannot have a very large capacity; however, it is easy to read and obtain challenge/response pairs (CRPs) of the PUF in a fusing state of the OTP due to limitations of the OTP itself, thereby deciphering a security key generated by the PUF from a device itself.